In general, a position detecting device is attached to a fluid pressure cylinder in order to detect the operating position of a piston and to use the detection signal as a signal for controlling the fluid pressure cylinder. This position detecting device detects the magnetism of a permanent magnet attached to the piston with a magnetically sensitive position sensor attached to the outer surface of the cylinder tube. In order to attach the position sensor to the outer surface of the cylinder tube, various mechanisms have been used.
For example, in Patent Document 1, there is disclosed such a position detecting device that a sensor holder having a sensor insertion groove having a narrow opening is attached to the outer surface of a cylinder tube with an attachment band (belt-like band), a position sensor is placed into the sensor insertion groove, and the position sensor is fixed to the sensor holder with a locking screw screwed into the position sensor. In this position detecting device, the position adjustment of the position sensor is performed by loosening the locking screw, moving the position sensor to the optimum detecting position in the sensor holder, and tightening the locking screw again at that position.
However, a method in which only a position sensor is moved to adjust the position as in this position detecting device lacks the flexibility in position adjustment. For example, when the attachment position of the attachment band relative to the cylinder tube is restricted, it is not enough to move the position sensor.
Position adjustment can also be performed by moving the sensor holder. However, in this case, it is necessary to connect the sensor holder and the attachment band with an attachment screw and an elongate hole, and the sensor holder is easily displaced in the direction of the elongate hole by vibration or the like.